Australia is at a cross roads as they react to a Varroa destructor incursion – will they take an elimination strategy or one of managing with the parasitic mite? Helping inform those on the ground at incursion response headquarters in New South Wales (NSW) has been leading Kiwi varroa expert Michelle Taylor, who recaps a whirlwind nine days working with the state’s Department of Primary Industries (DPI).
“The adrenaline's amazing,” Taylor says of the experience of being in the center of a country’s reaction to a biosecurity invasion.
“It's full on, everybody's in response mode. I thrive on that sort of thing, but it is exhausting.”
Varroa was first reported in Australia on June 22, but Taylor says they believe it may have been in the country for up to a year. The Plant and Food Research scientist is well across all those sorts of details, having been rushed over to the incursion headquarters in Orange, NSW, on July 4. There she spent nine straight days in meeting rooms, providing information that would aid the key decision makers.
Previous to the June 22 discovery, Australia was one of very few countries to which varroa had not spread. It landed on New Zealand’s shores in 2000 and, at that time, Taylor had just returned home from a stint working as a beekeeper-Masters student in North America and lent her knowledge of managing the mite to the incursion response. So, how do the experiences of the two countries align?
“First off, we are an island nation. So that makes it easier to contain varroa and plan a response. Australia has state borders that neither bees nor mites recognise. So this is probably their biggest challenge; Varroa was found in New South Wales, but with Queensland above them, Victoria below, and migratory beekeeping across the states that provide millions of dollars’ worth of pollination, they must work together to develop a plan to eradicate or manage varroa in Australia,” Taylor explains.
Varroa was first discovered in South Auckland, New Zealand, in April 2000, leaving almost six months before major hive migrations into kiwifruit pollination took place. In Australia’s case, almond pollination begins in late July, around a month after incursion day zero.
“Almond pollination largely takes place on the border areas between Victoria and New South Wales, requiring around 300,000 colonies. The almond industry is big, it's worth around $440 million so their support for the beekeeping industry will be crucial, as was support from our kiwifruit industry,” Taylor explains.
Three zones restricting beekeeping activity have been created in NSW. The 10km area surrounding the location where varroa have been found is called the “red” or “eradication” zone where honey bee hives are being euthanised. Further out, the 10-25km “surveillance” zones have officials monitoring and inspecting managed honey bee colonies to identify the extent of the incursion. The next 25-50km is called the “notification” zone where beekeepers must notify NSW DPI of the locations of their hives.
A month following the initial detection, almost 2500 managed colonies had been euthanised. Then there is the challenge of feral colonies, which could also carry and transmit varroa.
“In the first week of the incursion a back-of-the-envelop calculation suggested there could be around 15,000 colonies just in the initial areas of discovery. Since then, the landmass of eradication zone has increased quite a bit, so there'll be more than that. Successfully killing 15,000 feral colonies is a big task,” Taylor says.
She says the NSW and Australian biosecurity authorities are fast approaching the key decision of what strategy to take – seek eradication, or learn to live with varroa and take a “management” approach. The crucial information needed to make that decision is the completion of delimitation surveys which will help paint a picture of how widespread the mite is.
New Zealand’s varroa incursion responses in both the North and South Islands, were aided by emergency registration of miticide treatments that allowed for 24-hour treatment and “mite drop” assessments using sticky boards. However, Australia’s delimitation survey is relying on alcohol washes of a selection of bees from colonies to try and find varroa mites.
“The miticide and sticky board method we use in New Zealand kills about 82 percent of the mites on all of the adult bees within 24 hours, so it's pretty accurate. Whereas, the alcohol wash only kills mites on 300 bees (one percent of the adult bees). If varroa populations are small, which likely many in Australia will be at the moment, then they can easily be missed. The alcohol wash has its limitations but is better than nothing,” Taylor explains.
Aussie beekeepers are already preparing their management response and have been doing so for a number of years, aware that varroa would one day rear its head. Taylor says she has sometimes felt “part Australian” due to the amount of time her and colleague Mark Goodwin have spent presenting to Australian beekeeping conferences in the past 20 years, and she knows of numerous varroa-education missions to our shores from Aussie apiarists in that time. Since returning home last month, she has addressed Australian beekeepers via phone and video to continue that education.
“They are really concerned about whether they're going to be able to use their honey, or when they should be treating. There's a short game, and there's a long game. The long game requires prepping for both management and eradication, with the most important focus being the survival of honey bee colonies that meet the needs of Australia. We need to make sure that beekeepers understand how to manage varroa.
“It comes back to the same list of concepts that we provided our New Zealand beekeepers with. Central to this list is understanding varroa population growth and how this is impacted by the bee population and the source of varroa around the colonies, and when varroa populations need to be reduced. Alternating between chemical families is also vital to reduce the development of resistance.”
There is still hope among Australia’s biosecurity response team that their beekeepers can avoid management. Among beekeepers, Taylor believes there is uncertainty as they do not know what the final response will be.
“It's been a long process for Australian beekeepers. The varroa incursion they have long dreaded is now a reality, and now they're just waiting for clear advice for which way to move,” she says, adding “either way, beekeepers are resilient and they will adjust as required”.
